1. Field of the Invention
The present invention relates to a magnetic resonance imaging system and, in particular to a local coil for a magnetic resonance imaging system of the type composed of two separate coil parts.
2. Description of the Prior Art
In a magnetic resonance imaging (MRI) system, due to the application needs, some coils often comprise two parts separated from each other, such as a head-coil and a knee-coil, since there are usually two application needs in clinical practice, namely, the upper and lower parts of a head-coil are used together or the lower part thereof is used alone. Such coils usually are composed of two parts separated from each other. Under normal circumstances, the two parts of the coil which are separated from each other are each located in their own coil casings (housings) respectively.
In the present invention, for a simple description, the two parts of a separate type coil (the upper and lower two parts or the left and right two parts or two parts of other shapes) are referred to as the first partial coil and the second partial coil respectively. Accordingly the coil casing for the first partial coil to fit in is referred to as the first partial casing, the coil casing for the second partial coil to fit in is referred to as the second partial casing. FIG. 1a is an illustration of a separate type coil according to the prior art, and as shown in FIG. 1a, the separate type coil has a first partial coil 12 in the first partial casing 11 and a second partial coil 22 in a second partial casing 21. The second partial coil 22 is connected to a connector 24 for connecting to the imaging system via a second cable 23 which is disposed in the second partial casing 21. In FIG. 1a, assuming that the first partial coil 12 and the second partial coil 22 of the separate type coil comprise three coil units respectively, each coil unit corresponds to a cable. When the first partial coil 12 and the second partial coil 22 of the separate type coil are used together, in order to enable the correct output of the signals from the first partial coil 12, in FIG. 1a, the first cable 13 of the first partial coil 12 is disposed in the first partial casing 11, and the first cable 13 is connected to the connector 14 for connecting to the imaging system. Three coil units of the first partial coil 12 each lead to a cable 13 respectively from the first partial casing 11, the leading cables 13 are connected to the connector 14, and the signals of the first partial coil 12 are outputted to the imaging system for constructing images via the cables 13 and the connector 14. In this method, since the cable 13 and the connector 14 of the first partial coil 12 need to take up additional space, it is not convenient in use.
FIG. 1b is an illustration of another separate type coil according to the prior art, in FIG. 1b, the cables 13 and the connector 14 of the first partial coil 12 are disposed in the second partial casing 21, and the signals of the first partial coil 12 are connected to the cables 13 and the connector 14 in the second partial casing 21 by a metal sheet. As shown in FIG. 1b; the metal sheet is also divided into the upper and lower two parts, a first part 15 and a second part 25 of the metal sheet, wherein, the first part 15 of the metal sheet is located in the first partial casing 11, and connected to the first partial coil 12, the second part 25 of the metal sheet is located in the second partial casing 21, and connected to the connector 14 via the cable 13 in the second partial casing 21. The connector 24 connected to the metal sheet 25 and the connector 24 connected to the second partial coil 22 can be arranged side by side together, like the connector 4 shown in FIG. 1b. However, in this method, as the coil is used over time, the surface of the metal sheet will be rusted or contaminated, thereby causing imperfect electric contacts, in addition, when the second partial coil 22 is used alone, the second part 25 of the uncovered metal sheet will also cause some potential safety problems to a patient.